<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>triangle area</title>
    <script>
        alert("求三角形面积：")
        let high=prompt("请数入高");
        let width=prompt("请数入底");
        document.write("三角形的面积为:"+(high*width)/2)
    </script>
</head>
<body>

</body>
</html>